A method of encoding and/or decoding data is described, having the steps of: generating a challenge code, the challenge code being based on a pattern associated with at least one challenge arrangement having duplicated signs, encrypting the challenge code using a one-way hashing function to obtain a temporary encryption key, generating encoded data by encoding the data using a two-way transcoding function using the obtained temporary encryption key, wherein data is decoded using the two-way transcoding function and a subsequently obtained user temporary encryption key when the subsequently obtained user temporary encryption key matches the previously obtained temporary encryption key used to encode the data.